This invention relates to a novel organic mixed complex composed of 7,7,8,8-tetracyanoquinodimethane (hereinafter referred to as TCNQ) plus a certain derivative of TCNQ as the acceptor and an N-alkyl nitrogen-containing heterocyclic compound as the donor.
Electroconductive organic compounds are characterized in that they are light in weight, show anisotropy, can be processed or shaped with ease and can undergo chemical modification. Therefore, they are currently attracting much attention.
Typical of such electroconductive organic compounds are TCNQ complexes composed of nitrogen-containing heterocyclic compounds on one hand and TCNQ on the other. Among the relevant references, there may be mentioned "Synthesis and Application of Organic Semiconductor Materials", published by K.K. C.M.C., 1981, and "Gendai Kagaku (Modern Chemistry)", published by K.K. Tokyo Kagaku Dojin, No. 141, pages 12-19, 1982.
A Japanese patent application laid open under Kokai No. 254561/86 discloses a TCNQ complex composed of a nitrogen-containing heterocyclic compound cation, TCNQ anion radical and neutral TCNQ.
A Japanese patent application laid open under Kokai No. 204173/86 discloses a 1:1 or 1:2 complex between a specific 7-membered nitrogen-containing heterocyclic compound and TCNQ.
However, the above-mentioned TCNQ complexes each has a relatively high melting point (for example, the 1:2 complex between such nitrogen-containing heterocyclic compound and TCNQ generally has a melting point above 200.degree. C.), hence processing or shaping thereof is subject to restriction, although they have high electroconductivity. Accordingly, it is highly desirable to develop electroconductive organic compounds lower in melting point.
Under these circumstances, the present invention has been completed as a result of searching for organic complexes lower in melting point as compared with the prior art TCNQ complexes.